A view of strategy, procurement, warships, navies, and world politics. please note its all my work - information may come from elsewhere, and certainly the pictures do, but the analysis is mine, so any flak about it; address it to me, any praise likewise.
I have no problem with defending by debate or being corrected when I am wrong. I hope to someday get some of the ideas published, so any feed back will be of great and most profound assistance.

Wednesday, 16 September 2009

Is there a possibility for Amphibiosity in coversion?

Concept

A good fast containership hull would be an economical starting point for a new generation aircraft carrier. The hull of a containership is open and empty, so naval architects can fit in accommodation, fuel tanks, magazines and hangar decks, and on top of it all, the flight deck needed for an aircraft carrier. For the cost of two ships now building, we could have four or more. After all, apart from planned dry-dock time, ships sometimes don’t pass in the night, but instead suffer accidents, and with just two carriers available, the danger is that one will be undergoing a refit and the other damage.

(Wragg, 2009, pp. 189-90)

This is not a new concept, the MAC ships in World War II were key to the efforts against the wolf packs, Atlantic Conveyor was at points in time the most important vessel sent to the Falklands War – and was certainly the greatest strategic loss. Full conversion is requirement of some major changes on the ships though; hence the first section of this piece focuses on practicability, and it is only after that capability will be considered.

Practicability

As Wragg makes clear these vessels are open spaces, in fact almost blank canvasses; only better. Due the fact that they are designed to be strong, even without a top deck to complete them, the addition of such a deck will only add their capability.

They are built with range; they do their journey’s with no chance of an at Replenishment At Sea, they are built with speed; time is money, and they are built big; this means it is literally a case of building a top and a hangar, with a large flex bay underneath – far larger and therefore more flexible than the ones which have shown to be off such use in the Danish Absalom class and the American LCS designs; with the freeness offered by their initial design there is no reason why, that with the provision hydraulic bomb doors, that the lifts and ramps could not service both decks – therefore providing maximum internal mobility and force capability.

It would also be a lot cheaper than building a brand new third aircraft carrier or a pair of LHDs; especially in Britain’s case, as they could all be put together in one yard. This would highlight the quality of that yard for civilian contracts, whilst also providing a very capable vessel for the RN at a cost of under £1billion per unit.

The most complicated part of the conversion will be the re-sitting of the superstructure; and the changing of the engine and power generation arrangement. The former is relatively simple due to the fact that ship is to be built up/filled in as part of the conversion any way; it depends upon the design chosen, and whether American, British or French practices are chosen. The power plant is more complicated as depending upon island position, propulsion system chosen and whether or not it requires a funnel to evacuate steam/fumes; if the American Island system is followed, with it mounted to the rear, then the power plant may have to be barely altered from its current arrangement.

Due the power, size and stability available in the design a relatively heavy weapons fit could be included for the benefit of both operational and tactical strategic capability. For example a heavy CIWS outfit of 4x SeaRam and 4x Mk110 BAE 57mm could be installed in complimentary pairs to provide defence against any missiles, small boats or aircraft which penetrate the perimeter. A perimeter which could be further enhanced by the inclusion of the Mk41 VLS loaded with SM-3 ABM, Aster 30 & 15, Tomahawk TLCM and ASROC. This along with the inclusion of the sensors and systems off the T45 destroyer; would allow the vessels to be fully multi-role and capable, as well as reducing the requirement for close escort.

Problems

The limitations are obvious; any design is being built in a confined space, an already built hull. Whilst it is a hull which is large, roomy and undeveloped; in a simple phrase, it is a ‘blank canvass’. It is still an already built hull, many will certainly contest that survivability is better included in a hull which is built for purpose – some would even contest it is cheaper to build an equivalent vessel from scratch than to convert. The other area of contention and problems will be the capability of stores/support mechanisms that can be put into such a vessel and its ability to deal with top weight for all operations. This author would contest that with all these questions and arguments they would be topics of further study, but are nothing that good Naval Architect could not overcome with a little thought.

Capability

A conversion is likely to produce a highly capable ship; but any aircraft carrying vessel (even one of an amphibious focus) is judged by its capacity for aircraft, not its capacity in any other role. This is conversion hover, is not just about producing an aircraft carrier, it is primarily envisaged as an LHA. Therefore it is fitting it should be fitted with ramp for Griffon Hovercraft; the same craft which are currently deployed upon the RN’s serving LPH, HMS Ocean, with much success. Ably bracketed by 4 LCVPs on davits; this is tradition in the commando carrier concept and is something which adds very interesting dimension into possible force multiplication.

The various roles require quite different air groups; the size and composition of which will depend upon the size of container ship converted. TEU’s are containers, and container ships are classed by how many they can carry. The specifications given at the end of this, and therefore the air groups are for the conversion of vessel that carries 6-8000 TEUs; there are larger vessels available, some carrying as many as 12000 TEUs. The important thing about the 6-8000 TEU container ships, are they represent the best balance of size, manoeuvrability and possibility if they are converted – there larger ones are really to large; the smaller ones are two small.

Ideally the smaller 6000 TEU ship could accommodate, in theory, its hangar and air group of 44 aircraft including either E-2D Hawkeye AWACs or Chinook Heavy Lift helicopters. Whilst the larger, 8000 TEU vessel, would accommodate the same air group of about 44 aircraft; such a vessel would have the advantage of developing a far more potent sortie rate. This would be down to its greater space for workshops and other support facilities required to maintain the capability of aircraft and their weapon systems.

There are constraints in any design though, Hawkeye’s & the cheaper and better F-35c JSF & the current envisage generation of UAVs all require catapults; this is something which could easily be built in (and AWACs are an aircraft carriers best force multiplier). It is though a decision which will need to be made at the design stage. Such decisions are crucial, a ship may be in service with the navy for 40 years, therefore whatever restrictions are imposed at the beginning, cannot be easily rectified (in the catapults case, without some major re-piping or re-wiring), and certainly not replaced in service for up to 4 decades.

The flex deck, is another key enabler of this container ship conversion, its ability to be re-modulated and refocused would allow 1600 personnel to be carried its assault amphibious role. Slightly less for the longer term deployment of conflict stabilisation a smaller contingent of 1000 personnel would be carried, with the space being converted to increase internal food storage and recreational facilities in line with the requirements of its longer deployments. In carrier mode, the flex deck could be converted to either stores, extra hangar space further increasing the aircraft capacity or it could be a true commando carrier and accommodate 800 personnel; to provide any battle group that it is a component of with a light strike/raiding and even emergency conflict stabilisation force.

Conclusion

When in future the British government deploys the RN, for whatever role, in its current situation it is going have to watch timing very careful, or else it will be deploying forces with no air cover. The purpose built carriers of the Queen Elizabeth class will if built number just two, and there will be periods when neither will be operational. Added to this there is proof in the success of HMS Ocean, in the necessity of an air assault component in the amphibious fleet. The answer to this question, especially in the time of financial strictures, is obvious to the mind of this author in light of what has been discovered and discussed in the course of this work.

A class of 3 (or perhaps 4...we can hope) converted container ships would fit the requirements of the possible roles very successfully and at a cost most affordable to the nation. The benefits of having vessels; which in turn could provide an alternative or supplementary carrier battle group when such is the need; the core of amphibious task group; or the keystone of any sea based conflict stabilisation and management that the British government wishes to engage in are great. Such vessels, especially armed as suggested, would provide the currently very overstretched RN with a multi-versatile core from which its other forces and capabilities could projected with the necessary levels of support and security.

Further more if they were designed to be capable (and were in fact capable of doing so) of carrying the ‘commando carrier’ load then they really would be ‘Woolworths Carriers’; a good quality vessel for all occasions, not spectacular, but not something to be discounted.

Specifications: that must be asked for (Based on the Conversion of a 6-8000 TEU container ship)

2 Equipment lifts; each capable of moving a standard under-slung load (up to a 4x4 vehicle) or weapons

Hangar Deck/Flex Deck underneath

Ski Jump + a Single Catapult would be best for the development of operational capability on a budget and would have best interoperability with the currently envisaged Queen Elizabeth class; however if these are in the end not built then 2 Catapults would be needed.

Assault operations

stern ramp allowing for the operation of 4 Griffon Hovercraft

davits for LCVPs, the stern ramp must be able to support a Mexifloat or similar to provide for an easier operational loading/offloading.

There will need to be spots to allow for 2 Chinook and 4 Merlin’s to be operate simultaneously in assault prep.

Alex, as long as they Navy is wholly focused on projecting power ashore against Third World dictators, or trying to stop China from invading Taiwan, they will have no time or money for alternatives like this. We must get spending priorities straight or we lose our edge. The West having been at the forefront of change for centuries, is now wholly committed to the declining dominance of carrier air, when there are so many other power projection alternatives, as well as needs for the small low tech warship and auxiliaries.

the trouble is this type of vessel would be perfect for those kinds of operations in those kinds of wars; although I personally think that specialised vessels for the warships will be always present. I do wonder about the non-sinking amphibs and the future aviation ships - so many large hulls already available...however, it is capacity for workshops and systems that will be key.

some good points were raised, but the whole point about a more permanent conversion and the use of pod propuslion is that these ships can be 'quite' manouverable - nothing of the order of 50,000, in fact even 30,000 tons is ever going to be manouverable enough; especially when avoiding a missile comining in at Mach 3. With your idea containerised CIWS weapons could be installed, which would allow for security.

In this one, ideally it would (along with its Air Group and its supporting Escorts) have a 4 Sea RAM CIWS and 4 BAE Mk110 57mm as well as two Mk41 VLS loaded with various missiles of its own; in other words its aim is to stop the missile before it hits the ship. Added to this the open space of the hull would allow for some quite heavy levels of subdivision, stabilisation and anti sinking systems to be installed.

However; the key with these ships is the space they have to put into supporting their airgroup, supporting their troops - that is their true advantage.

this is where we diverge; what you are talking about is cheap and quick wartime conversion; what I am talking about is full time fleet ship; a full conversion, no containers, the hull be used as blank canvass with proper decks put in a - a complete rebuild in manyways. My ship would be a non-expendable asset...well all assets are expendable but it would not be one to which this would be readily described it would be to useful.

The ship I am proposing would be a class of three vessels, to provide the RN/RM amphibious Task group with the LHA it desperately needs, as well as the core of an influence squadron and even a back up carrier when operational required - I am talking about making proper warships out of them. I am talking about this from the RN perspective - which needs ships of these capabilities.

Also Pod Propulsion is probably going to become standard on the new 8-12-???000 TEU vessels as it has been found to be far less maintenance intesive, more energy efficient as well as more able to manouver in busy ports...and shipping lanes. However, for the purposes of my design would put in as part of the rebuild.

3 comments:

Alex, as long as they Navy is wholly focused on projecting power ashore against Third World dictators, or trying to stop China from invading Taiwan, they will have no time or money for alternatives like this. We must get spending priorities straight or we lose our edge. The West having been at the forefront of change for centuries, is now wholly committed to the declining dominance of carrier air, when there are so many other power projection alternatives, as well as needs for the small low tech warship and auxiliaries.

I had been giving some thought to this subject too (Containership Conversions CC.) Some parameters. The chances of a surface ship surviving a modern naval engagement unscathed is practically nil. Containerships are optimized to cruise at 27 knots and has neglible capacity to maneuver. They are easy targets. If not sunk they will likely suffer enough damage to require port repairs. A CC ship is therefore good for only a single battle and its loss must be expected. Equipment must be quick and dirty. And plenty cheap too.

A CC's best defense against being sunk is its huge volume, too big for even a number of missiles and bombs to sink. This defense is enhanced with empty containers that act as space armor and as bouyancy cells. Containers filled with sandbags and fire suppression foam systems can protect selected equipment.

Another advantage of CCs is that ordinary ship operations are largely automated and require only a crew of 12 to man even for the largest ship. The rest of the war footing crew can then be military personnel for just aircraft operations. 24 Su 27s is enough to form a credible deterence. This manning is at most one or two hundred instead of the 5 to 6 thousand in a USN super-carrier.

All high tech sensors, weapons systems and their specialists will be manned from accompanying destroyers and frigates. The large CCs form a very useful and effective shields (sacrificial ships) for these high value naval ships for can hide behind the CCs in the event of an incoming missile attack.

The CC plies its trade as an ordinary containership in peacetime. Its already paid for should it be sunk in wartime. In wartime it is quickly converted by adding a baqre bones long angled flight deck, long enough for navalized Su 27s to take off without catapults and to land without arrestor wires (may still need them.) All support supplies and equipment can be prepackaged onshore in containers and quickly loaded. It is cheap enough to sail several such CCs (useful redundency)for each mission. Their mission is not to challenge the USN carrier group in a one to one brawl. That will be a pointless bloodletting for both sides. In a real fight it will be missiles not planes vs planes or planes against ships. The usefulness in China carrier based aircraft is to establish a trip wire where the USN will think thrice before sailing a USN carrier group to intimidate China.

Such a CC will have the island on the stern port corner so that the angled deck runs forward from starboard stern to the port bow. This leaves room for an aircraft park on the starboard bow area. There is a "hatch" or two that are not aircraft lifts. Two long boom cranes one on the island and one at the aircraft deck park (design proposal) will be used to transfer aircraft to and from below deck, to remove wrecks and to transfer aircraft to a separate repair ship. All the mother CC does is to fuel/refuel and arm/rearm the planes. They are not required to undertake major repairs (re. single mission parameter.) The quick-built conversion need not be durable or stressed for bad weather. Current ships already use weather forcasting to avoid bad sailing conditions. Aircraft launch and recovery will be under close to ideal weather conditions. This should avoid the requirement for sophisticated equipment and procedures, factors often cited for phoo-phooing China's ability to field a carrier force.

The mission of a Chinese CC aircraft carrier is to keep the USN carrier group (no other navy is a threat)as far offshore from China as possible in the event of tensions. A patrol line 200 miles off the coast is plenty and the PLAN ships enjoy the protection of shore based defenses. 200 miles is close enough to port not to risk losing one too many damaged ships.

If operations require it replacement ships will quickly be converted. China has plenty of large containerships that will be idled anyway in time of war.

1.) A CC needs only one or two fully loaded runs to make back its original cost. Anything beyond two runs is pure profit. Losing an older but fully functional CC is no big deal. For instance, in the current shipping slump many perfectly good CCs are being scrapped as keeping them idled costs more than they are worth.

2.) CCs are powered by giant low speed two stroke diesels that cannot change revolutions easily. They are well tested high efficiency and high reliability engines. The single prop is sized to the engines revolutions to provide maximum efficiency. The propshaft is connected directly to the engine's output shaft. There is no gearbox. The engines are started with compressed air. To reverse the engine is stopped and compressed air used to restart the engine in the opposite direction. Since a CC's stopping distance is several miles every maneuver has to be preprogrammed more than an hour ahead. If you want to bomb a CC it will be impossible to miss.

To install podded engines is to contradict the whole basis of using existing CCs in wartime service. Podded engines have no place in commercial CC trade as they have unneeded capabilities plus the complexity will require more crew hands. No podded CCs will be at hand for quick conversion to wartime duties.

3) No ship can outmaneuver a guided missile. In the event of a missile attack the CC should act as a bomb magnet to draw the poison to itself and away from more expensive and critical naval assets. In so doing it also defangs the attacking force. The idea is not survivability per se but to survive long enough to defang the enemy and to let the crew abandon ship in an orderly manner. Therefore you want to have as few crew onboard as possible.

4) A damaged ship has only scrap value. A sunken one is a small loss. One or two of the enemy's missiles will probaly cost more than the CC is worth, a very profitable exchange.

5) Cheap functionality means that it will be practical to field a few similarly converted CCs to provide alternative landing decks for recovering aircraft. It also means more bomb magnets. Attrition in missiles and other equipment will compromise the enemy's ability to sustain offensive operations.